1. Field of the Invention
This invention relates to FET semiconductor devices and more particularly to channel structures and methods of manufacture thereof.
2. Description of Related Art
Problems with thin film transistors include limited hole mobility .mu..sub.p, insufficient transconductance, and inadequate hot carrier immunity. Silicon devices are limited by a high bandgap E.sub.g of about 1.12 eV which restricts hole mobility and transconductance.
U.S. Pat. No. 5,089,428 of Verret et al for "Method for Forming a Germanium Layer and a Heterojunction Bipolar Transistor" shows use of SiGe layers in semiconductor devices as a buffer between a P- Ge layer and an N -Si substrate. The N- Ge.sub.x Si.sub.1-x layer is deposited onto the N- Si by CVD.